Mesoscale Precipitation Discussion 0617
NWS Weather Prediction Center College Park MD
537 PM EDT Wed Aug 08 2018

Areas affected...SoutheastArizona to Southwest New Mexico

Concerning...Heavy rainfall...Flash flooding possible

Valid 082136Z - 090310Z

Summary....Flash flooding is possible over portions of southeast
Arizona into southwest New Mexico during the remainder of the
afternoon and early evening.

Discussion...Convection was beginning to develop over southeast
Arizona and southwest New Mexico, especially over the higher
terrain of the Mogollon Rim and eastward into portions of southern
New Mexico.  While the plume of deepest moisture and greatest
MLCAPE and SBCAPE is actually west of the area, CAPE values were
still between 1500 J per kg and 2500 J per kg over the terrain. 
Precipitable water values in the outlook area were running between
1.00 inch and 1.25 inches.  Thus continue to anticipate the
potential for locally intense rainfall rates.

This area was located on the northern periphery of cyclonic shear
from a mid/upper level circulation making its way across northern
Mexico as seen on GOES-16 Low Level Water Vapor channel/7.3
micrometers.

High resolution guidance shows this area to have the highest
probabilities of rainfall rates exceeding 1 inch per hour into the
evening hours, with the 08/19Z HRRR-Time Lagged Ensemble even
showing a small area of 20 percent exceedance of 2 inches per 3
hours hour after 09/00Z along the International Border in southern
Arizona.

Given the potential for cell mergers, an elevated heat source that
persists into the early evening hours, feel that a localized flash
flood threat exists.

Bann

ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC...

ATTN...RFC...CBRFC...WGRFC...

LAT...LON   35561229 34531107 33940980 33690818 33580774
            33480695 33790540 32620533 32060582 31860690
            31840769 31850800 31790817 31640817 31480816
            31380833 31360960 31341023 31501123 33001130
            33901214 34531257 35221280 35541268